Struct SubgroupHeader

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pub struct SubgroupHeader {
    pub header_type: u8,
    pub track_alias: VarInt,
    pub group_id: VarInt,
    pub subgroup_id: VarInt,
    pub publisher_priority: Option<u8>,
}

Fields§

§header_type: u8§track_alias: VarInt§group_id: VarInt§subgroup_id: VarInt§publisher_priority: Option<u8>

Implementations§

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impl SubgroupHeader

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pub fn decode(buf: &mut impl Buf) -> Result<Self, CodecError>

Decode a subgroup header, Type Flags field included.

The field is read as a whole varint of whatever width the sender used, and the value it decodes to is what the three Section 11.3.1 conditions are applied to. A non-minimal spelling of a valid value is accepted: 0x8010 decodes to 16, which is a legal Type Flags, and this reads it. See the module documentation for why the draft leaves that open and why permissive-on-receive is the choice here; the encoder is the strict half and always writes the one-byte form.

The whole field is read, which is what lets stream_type_error tell a padding or SETUP stream — both assigned, both several bytes wide — from a Type Table 2 does not assign.

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pub fn encode(&self, buf: &mut impl BufMut)

Serialize the header exactly as its Type byte describes it.

Infallible, and so willing to write a Type draft-23 Section 11.3.1 tells an endpoint to reject — including a reserved-mode Type this module’s own Self::decode refuses to read back. Prefer Self::encode_checked, which refuses those Types instead.

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pub fn encode_checked(&self, buf: &mut impl BufMut) -> Result<(), CodecError>

Serialize the header, refusing a Type value draft-23 forbids.

Errors with CodecError::InvalidField for exactly the Types draft-23 Section 11.3.1 lists as invalid (the same set Self::decode refuses), before any byte is written, so a refused header leaves buf untouched. Everything else is written by Self::encode.

The check belongs on the encode side as well as the decode side because the two halves would otherwise disagree about which streams exist: a reserved-mode header written by Self::encode cannot be read back by Self::decode, and a codec used to rewrite captured traffic would emit a stream it could not then parse.

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pub fn has_properties(&self) -> bool

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pub fn subgroup_id_mode(&self) -> u8

The subgroup-ID mode: (header_type & 0x06) >> 1.

0 = no subgroup ID on the wire and it is zero; 1 = the subgroup ID is the first object’s ID; 2 = an explicit ID follows the Group ID; 3 = reserved. Exposed because the mask is module-private and dispatch::AnySubgroupHeader::subgroup_id_mode cannot read it.

3 never comes back from Self::decode, which refuses the Types carrying it. header_type is a public field, so a hand-built header can still report it; Self::encode_checked is what refuses to put one on the wire.

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